Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University , 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Biomacromolecules. 2017 Dec 11;18(12):4393-4404. doi: 10.1021/acs.biomac.7b01452. Epub 2017 Nov 21.
Cellulose nanofibrils (CNF) offer great prospects as a natural stabilizer of colloidal dispersions and complex fluids for application in food, pharma, and cosmetics. In this study, an ionic surfactant (sodium dodecyl sulfate, SDS) was used as emulsifier of oil-in-water and water-in-oil emulsions that were further costabilized by addition of CNF. The adsorption properties of SDS in both, CNF dispersions and emulsions, as well as the influence of composition (CNF and SDS concentration) and formulation (ionic strength, oil, and CNF types) on the phase behavior were elucidated and described in the framework of Windsor systems. At low salinity, the phase transition of emulsions containing CNF and SDS at low concentrations was controlled by molecular transfer in the oil-in-water system. Irregular droplets and "bi-continuous" morphologies were observed at medium and high salinity for systems containing high CNF and SDS concentrations. Water-in-oil emulsions were only possible at high salinity and SDS concentrations in the presence of small amounts of CNF. The results revealed some subtle differences in CNF interfacial activity, depending on the method used for their isolation via fiber deconstruction, either from microfluidization or aqueous counter collision. Overall, we propose that the control of emulsion morphology and stability by addition of CNF opens the possibility of developing environmentally friendly complex systems that display high stability and respond to ionic strength following the expectations of classical emulsion systems.
纤维素纳米纤维 (CNF) 作为胶体分散体和复杂流体的天然稳定剂，在食品、制药和化妆品领域具有广阔的应用前景。在本研究中，离子表面活性剂（十二烷基硫酸钠，SDS）被用作水包油和油包水乳液的乳化剂，通过添加 CNF 进一步稳定乳液。SDS 在 CNF 分散体和乳液中的吸附特性，以及组成（CNF 和 SDS 浓度）和配方（离子强度、油和 CNF 类型）对相行为的影响，均在温莎体系的框架内得到阐明和描述。在低盐度下，含有低浓度 CNF 和 SDS 的乳液的相转变受油包水体系中分子传递的控制。对于含有高浓度 CNF 和 SDS 的体系，在中高盐度下观察到不规则液滴和“双连续”形态。只有在高盐度和 SDS 浓度下，并且存在少量 CNF 的情况下，才有可能形成水包油乳液。结果表明，根据通过纤维解构分离 CNF 所采用的方法（微流化或水对撞），CNF 的界面活性存在一些细微差异。总体而言，我们提出通过添加 CNF 控制乳液形态和稳定性，为开发具有高稳定性并响应离子强度的环保复杂体系提供了可能性，这符合经典乳液体系的预期。
